Description: Immunodeficient mice are being used as a means to grow both normal and transformed cells and/or tissues in vivo. Athymic mice (nu/nu, Balb background) and severe combined immunodeficient (SCID, C.B.-17 scid/scid) mice are being utilized. The resource provides mice for cancer-related studies, housing and maintenance of animals, and resource personnel to facilitate in vivo experiments. Biosafety Level (BSL) 2 and 3 facilities are available within the resource. The shared resource is located in two separate animal facilities, both under the jurisdiction of the Campus Veterinarian and accredited by the American Association for the Accreditation of Laboratory Animal Care (AAALAC). The second floor of Warren Hall contains three rooms used by the shared resource. A 600 sq. ft. room is used for housing colonies of nudes and SCIDs, for surgical procedures to implant human fetal tissues into SCID mice, and for housing experimental mice. The other two rooms of this facility house experimental animals. One room of 300 sq. ft. is used for BSL 2 studies and can house 175 cages of SCID mice. The facility is used exclusively for cancer-related research. Current studies include oncogenesis, metastasis, and gene transfer with replication-defective vectors. The BSL 3 Facility is 400 sq. ft. and capable of housing 150 mouse cages. It is used to house SCIDhuman mice infected with human retroviruses. A portion of the studies in this facility are cancer related, the rest are AIDS related. Current Center-supported studies include in vivo models of HTLV-induced leukemogenesis. The Core SCID breeding colony is housed in the Center for Health Sciences. Access to the colony is limited to individuals trained in animal husbandry. At present, 30 nu/nu breeding sets are maintained with production of 30-40 pups per month. The SCID facility maintains 75 breeding pairs and produces 250 SCID pups per month. Weaned SCIDS from the core breeding facility are transferred to the Warren Hall facility for use in experiments. Animals in both facilities are maintained under microisolation. As an added precaution, SCID and breeding nude mice are housed in laminar flow racks.